Fluororesin, manufacturing method therefor, composition, and article

Abstract

A fluororesin having excellent storage stability with a solvent and adhesion to a base material; a method of its production; a composition including the fluororesin and a solvent; and an article including the composition. The fluororesin includes a polymer having a fluorine-containing aliphatic ring structure within a main chain comprising at least one of an alkoxycarbonyl group having an alkoxy group of 1 to 3 carbon atoms and an amide group having a coupling group. An IR spectrum of a 200 μm thick cast film of the fluororesin satisfies 0.010≤B/A≤0.7 where A is a local maximum absorbance at 1,780 to 1,800 cm−1, measured from a straight line connecting an absorbance at 1,700 cm−1 and an absorbance at 1,925 cm−1, and B is an absorbance at 1,720 cm−1, measured from a straight line connecting an absorbance at 1,647 cm−1 and an absorbance at 1,763 cm−1.

1 . A fluororesin composed only of a polymer having a fluorine-containing aliphatic ring structure within a main chain,
 wherein the polymer comprises at least one of an alkoxycarbonyl group having an alkoxy group of 1 to 3 carbon atoms and an amide group having a coupling group, and   a cast film comprising the fluororesin with a thickness of 200 μm satisfies the following Formula 1 in an infrared spectrum measured by a transmission method with a Fourier transform infrared spectrophotometer,
   0.010 ≤B/A≤ 0.7  Formula 1
 
   wherein A indicates a local maximum value of an absorbance at a wave number of 1,780 to 1,800 cm −1  due to absorption of the alkoxycarbonyl group, using a straight line connecting an absorbance at a wave number of 1,700 cm −1  and an absorbance at a wave number of 1,925 cm −1  as a baseline, and   B indicates an absorbance value at a wave number of 1,720 cm −1  due to absorption of the amide group, using a straight line connecting an absorbance at a wave number of 1,647 cm −1  and an absorbance at a wave number of 1,763 cm −1  as a baseline.   
     
     
         2 . The fluororesin according to  claim 1 , which has a mass average molecular weight of 10,000 to 500,000. 
     
     
         3 . The fluororesin according to  claim 1 , wherein the polymer comprises a unit having a fluorine-containing aliphatic ring structure constituting a main chain. 
     
     
         4 . The fluororesin according to  claim 3 , wherein the unit having a fluorine-containing aliphatic ring structure constituting a main chain is at least one selected from the group consisting of a unit formed by cyclopolymerization of a diene-based fluorine-containing monomer, and a unit based on a cyclic fluorine-containing monomer. 
     
     
         5 . The fluororesin according to  claim 1 , wherein
 the coupling group is represented by the following Formula 2:
   —SiR 1 R 2 R 3   Formula 2
 
   wherein each of R 1 , R 2  and R 3  independently represents an alkoxy group having 1 to 3 carbon atoms or an alkyl group having 1 to 3 carbon atoms, and   at least one of R 1 , R 2  and R 3  is the alkoxy group.   
     
     
         6 . The fluororesin according to  claim 1 , wherein the amide group is represented by the following Formula 3:
   —CONH—R 4 —SiR 1 R 2 R 3   Formula 3
   wherein each of R 1 , R 2  and R 3  independently represents an alkoxy group having 1 to 3 carbon atoms or an alkyl group having 1 to 3 carbon atoms,   at least one of R 1 , R 2  and R 3  is the alkoxy group, and   R 4  is an alkylene group, a group having an imino group between carbon atoms of an alkylene group, or an arylene group.   
     
     
         7 . The fluororesin according to  claim 1 , wherein the alkoxycarbonyl group and the amide group are each present at an end of a main chain of the polymer. 
     
     
         8 . A method for producing the fluororesin according to  claim 1 , the method comprising:
 preparing a first solution by dissolving, in a first solvent, a first fluororesin composed only of a first polymer having a fluorine-containing aliphatic ring structure within a main chain and in which the first polymer comprises the alkoxycarbonyl group;   preparing a second solution by dissolving a compound having a coupling group and an amino group in a second solvent that is compatible with the first solvent; and   mixing the first solution and the second solution and converting 10 to 50% of the alkoxycarbonyl group, calculated as a value of the A, into an amide group by a reaction with the compound.   
     
     
         9 . The production method according to  claim 8 , wherein in a second fluororesin composed only of a second polymer having a fluorine-containing aliphatic ring structure within a main chain and in which the second polymer comprises an unstable group at an end of the main chain,
 50 to 100 mol % of the unstable group is converted into a carboxylic acid fluoride group by heating in the presence of molecular oxygen to obtain a third fluororesin, and   the carboxylic acid fluoride group of the third fluororesin is converted into the alkoxycarbonyl group by a reaction with an alcohol having 1 to 3 carbon atoms to obtain the first fluororesin.   
     
     
         10 . A composition comprising the fluororesin according to  claim 1  and a solvent. 
     
     
         11 . An article comprising a coating film of the composition according to  claim 10  on a base material.